Welcome to Azeroth Darlingen!

In the top right-hand corner of this forum you will see the ‘Account’ button which will take you directly to Battle.net Account Management. From there, you should click the game account you wish to add game time to. There will be a ‘Buy Game Time/Subscription’ menu option and from there you will be taken to a payment page (similar to the ones you see when shopping on other Internet sites). There will be several payment options open to you, select the right one, fill in the details and once the payment is processed, your game time will be added to your account. =)

For more information, have a read of this support article:

Setting Up and Managing Your Subscription
http://eu.battle.net/support/en/article/setting-up-and-managing-your-subscription

And if you have any additional questions for us then feel free to add to this forum thread.